Wolnelektury plugin

The plugin seems to work fine, but there is a minor issue with downloading. EPUBs, MOBIs and FB2s get correct filenames, metadata and even covers, while PDFs and TXTs get filenames broken (additional chars in front of the name that look like taken from base64 set) and when I try to open them, the meassge box 'No such file or directory' pops up. And indeed there is no trace of them on my harddisk.